A computed tomography (CT) scan – sometimes called a CAT scan – is a noninvasive (no incision, no injection) medical test. CT scans help your physician diagnose and treat many types of medical conditions.
How CT Scans Work
Like x-rays, CT scans come in many varieties. Depending on your health issue, your physician may recommend a CT scan of your abdomen and pelvis, whole body, chest, head, sinuses, heart arteries, spine or other areas. But all CT scans basically work in the same way.
They are like typical x-ray exams. X-rays are a form of radiation–like light or radio waves–that can be directed at the body. Different body parts absorb the x-rays in varying degrees. But unlike an x-ray, a CT scan takes many more images at many different angles.
With CT scanning, many x-ray beams and a set of electronic x-ray detectors rotate around you. These beams measure the amount of radiation your body absorbs. At the same time, the exam table moves slowly through the scanner so that the x-ray beam follows a spiral path. A special computer program processes this large volume of data to create two-dimensional, cross-sectional images of your body.
CT imaging is like looking into a loaf of bread by cutting the loaf into thin slices. When the image slices are reassembled by computer software, the result is a very detailed multidimensional view of the interior. The newer CT scanners used at Radiology & Imaging enable us to obtain multiple slices in a single rotation. Because the slices are thinner, the CT scan reveals more detail, more views and more information. Because the machine is much faster, you are exposed to less radiation. This is especially beneficial to children, the elderly and the critically ill.
Why Physicians Use CT Scans
Think of a CT scan as a combination of special x-ray equipment and sophisticated computers. It is an x-ray exam taken to a much, much higher level. Your physicians learn key information about the health of your internal organs, bones, soft tissues and blood vessels. The clarity and detail is much higher than with an x-ray exam. Your medical team can better evaluate your health and better plan the best ways to improve your health.
Preparing For Your CT Scan
Most CT scans do not require any special preparation. But do ask your physician. For a CT scan of your head, you may not be able to eat or drink anything for several hours before the exam.
Information the technologist and your physician need to know before the exam may include:
- The medications you are taking
- Any allergies
- Whether you are allergic to contrast material, or "dye" used in imaging exams
- Any recent illnesses
- Any serious medical condition
- If you have a history of heart disease, asthma, diabetes, kidney disease or thyroid problems
Our radiologist also needs to know if you have asthma, multiple myeloma or any disorder of the heart, kidneys or thyroid gland, or if you have diabetes—particularly if you are taking glucophage.
If you are a woman, do inform your physician and the Radiology & Imaging technologist if there is any possibility that you are pregnant.
Do wear comfortable, loose-fitting clothes. You may have to put on one of Radiology & Imaging’s exam gowns. Metal objects like jewelry, eyeglasses, dentures and hairpins may affect the CT images. When you can, leave those items at home. Or you can remove them just before your exam. You may also be asked to remove hearing aids and removable dental work.
Our experienced and board-certified radiologists can perform exams with or without intravenous contrast. With intravenous contrast, the radiology technologist injects a small amount of material into a vein in your arm. Contrast enables the equipment to produce a higher quality picture of your blood vessels and organs. Your physician may require intravenous contrast to help distinguish between normal and abnormal tissue. The technologist can discuss the risks and benefits of the contrast, which uncommonly may have potential side effects. You may also wish to discuss any concerns about contrast with your referring clinicians.
What The Exam Is Like
Your exam begins with the technologist positioning you on the CT exam table. Normally, you lie flat on your back or possibly on your side or on your stomach. The technologist may use straps and pillows to help you comfortably maintain the correct position and to hold still during your exam.
If a contrast material is used, it will be injected through an intravenous line (IV) into an arm vein. This material or dye helps detect tumors and locate areas of inflammation.
Next, the table will move quickly through the scanner to determine the correct starting position for the scans. Then, the table will move slowly through the machine as the actual CT scanning is performed.
You may need to hold your breath for a few seconds during portions of the scanning. Any motion, whether breathing or body movements, can cause blurring.
When you enter a Radiology & Imaging CT scanner, you may see lights. The lights help ensure we have you in the right position. During the exam you will hear only low buzzing, clicking and whirring sounds. Those are the sounds of the CT scanner revolving around you during the imaging process.
You will be alone during the scan but our technologist will be able to see, hear and speak with you at all times. If your child is having the exam and needs you there, you may be allowed in the room. You will have to wear a lead apron to prevent radiation exposure.
When your exam is completed, we will ask you to wait until the technologist verifies that the images are of high enough quality for your physician to interpret them.
Most people are in and out within 30 minutes. You can return to your normal activities without delay. If you received contrast material, you may be given special instructions.
The CT Scan’s Benefits & Risks
Both the benefits and risks of a CT scan are a bit higher than the risks of a typical x-ray. Major benefits of CT scans include that they:
- Are painless, noninvasive and accurate
- Show bone, soft tissue and blood vessels all in the same image
- Deliver very detailed images of many types of tissue – much more detailed than conventional x-rays
- Reveal specific information about your lungs, bones, blood vessels and other body parts
- Are fast and simple
- In emergencies, CT scans can reveal internal injuries and bleeding quickly enough to help save lives
- There are many more benefits listed here
While risks are minimal, they do exist. CT scans present a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs this risk. For example, a body CT scan will expose you to a radiation dose that is about equal to what the average person receives from background radiation over three to five years. Background radiation is the radiation that comes from natural environmental sources including the earth's crust, the atmosphere and cosmic rays.
Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant. It is an exam generally not recommended for pregnant women. Nursing mothers should wait for 24 hours after contrast material injection before resuming breast-feeding. And because children are more sensitive to radiation, they should have a CT study only if it is essential for making a diagnosis and should not have repeated CT studies unless absolutely necessary.
The CT Scan’s Limits
No exam meets every need. For soft-tissue details in the brain, internal pelvic organs, knee or shoulder, magnetic resonance imaging (MRI) works better than a CT scan. If you are pregnant, a CT scan is generally not recommended. A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table.
Come To Liberty Street Or Enfield For Your CT Scan
Radiology & Imaging features Helical CT scanners at our Enfield, Connecticut office. Like all Radiology & Imaging sites, this site is accredited by the American College of Radiology. You can receive a wide range of examinations in a comfortable outpatient environment at any of our facilities.
Subspecializing Means Greater Expertise & Accuracy
At Radiology & Imaging, our radiologists subspecialize in one or more of the many types of CT scans. Your radiologist may primarily read and interpret chest CT scans or abdomen and pelvis CT scans. Or your radiologist may subspecialize in another part of the body–head, sinuses or spine, for example. This means your images are analyzed by a physician with more experience, knowledge and training.
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